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    <h1 style="color: white;text-align: center;">数字圆</h1>
    <div class="back">
        <p class="p1"><span>1</span></p>
        <p class="p1"><span>2</span></p>
        <p class="p1"><span>3</span></p>
        <p class="p1"><span>4</span></p>
        <p class="p1"><span>5</span></p>
        <p class="p1"><span>6</span></p>
        <p class="p1"><span>7</span></p>
        <p class="p1"><span>8</span></p>
        <p class="p1"><span>9</span></p>
        <p class="p1"><span>10</span></p>
        <p class="p1"><span>11</span></p>
        <p class="p1"><span>12</span></p>
        <p class="p1"><span>13</span></p>
        <p class="p1"><span>14</span></p>
        <p class="p1"><span>15</span></p>
        <p class="p1"><span>16</span></p>
        <p class="p1"><span>17</span></p>
        <p class="p1"><span>18</span></p>
        <p class="p1"><span>19</span></p>
        <p class="p1"><span>20</span></p>
        <p class="p1"><span>21</span></p>
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